Sleep-activity rhythm disturbance is a prevalent, disabling symptom in patients with dementia. Disturbed sleep with night wandering may be the single most common cause for placing cognitively-impaired (CI) elders in nursing homes. Medical treatment has proven only minimally effective and has serious side effects. The pilot in five subjects demonstrated that an Individualized Activity Intervention in the daytime improved nocturnal sleep and affect, and reduced daytime napping in CI elders. Therefore, the specific aim of the proposed study is to evaluate the effect of an Individualized Activity Intervention on nocturnal sleep and psychological well-being of CI nursing home residents who demonstrate sleep-activity rhythm disturbance. This study will use a pretest-posttest experimental design with one intervention and one control group. Following the collection of baseline data for five days, the 90 subjects will be randomly assigned to receive either the Individualized Activity Intervention or to a control group. The purpose of the intervention is to replace frequent daytime napping episodes with meaningful activities. After a comprehensive assessment of the resident's current cognitive, physical, communication, sensory, and emotional status and past interests, the Principal Investigator will prescribe the activities for each resident in the experimental group. Examples of individualized activities include objects for tactile and visual stimulation, arts and crafts, and games. Trained Project Nursing Assistants will conduct the intervention for a minimum of one hour daily, in 15-30 minute sessions, seven days a week for three weeks. The time of day the intervention is administered will be based on the patterns of daytime napping during baseline, and observation of the resident for sleepiness. Twenty-four hour sleep-wake patterns will be measured using an actigraph on days 1-5 of baseline, and during the intervention on days 17-21. Psychological well-being will be assessed using the Dementia Mood Picture Test three times during baseline and three times during the Individualized activity Intervention. Analysis of covariance, with the mean baseline score for each measure serving as the covariate, will be used to determine whether the intervention and control groups differ.